Vibration at startup (HVAC related)?

SpacePony

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I love how quiet my Mach-E is, and the first few days I had it the temps were pretty moderate (in 50s and 60s). But the last few days have been in the mid/lower 40s. When I start the vehicle, there is some sort of vibration that you can feel through the brake & go pedals. It's not the climate fan speed (the one blowing air into the cabin), that fan is quiet and produces no vibration at any fan speed. But it's related to climate control because if you turn off climate control, the vibration stops immediately. And if you don't have climate control on when you start the vehicle, the vibration never occurs. Regardless, it usually goes away within a minute or two after cold startup in the cold.

Does anyone know what this secondary (presumably) fan vibration is that only occurs shortly after startup for a minute or two?





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fayt349

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Same behavior on mine. Hell it was like the same on my tesla model 3 too.
 

Kamuelaflyer

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Is it possible that the vibration is present even on our ICE cars but we simply fail to notice it due to the noise and vibrations from those engines?
 
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SpacePony

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Is it possible that the vibration is present even on our ICE cars but we simply fail to notice it due to the noise and vibrations from those engines?
Quite likely compared to an ICE. However 3 of my 4 previous cars have been electric (Volt, i3, Volt) and none of them had this "fan frenzy" at startup. I just didn't know if the vibration meant it was out-of-spec, or if it was something others were experiencing the same as I was.
 
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SpacePony

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Do you have e-heat enabled?
Yeah, it defaults to on when auto is set, right? I haven’t tried toggling e-heat on/off separately from the entire climate on/off to see if that’s related. I’ll try that next time it occurs.
 

mixduptransistor

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Quite likely compared to an ICE. However 3 of my 4 previous cars have been electric (Volt, i3, Volt) and none of them had this "fan frenzy" at startup. I just didn't know if the vibration meant it was out-of-spec, or if it was something others were experiencing the same as I was.
For all the issues people have reported, if there is something wrong with one of the systems they are pretty good about alerting you that it's throwing DTCs and it needs to go into service
 

Gimme_my_MME

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Yeah, it defaults to on when auto is set, right? I haven’t tried toggling e-heat on/off separately from the entire climate on/off to see if that’s related. I’ll try that next time it occurs.
It does not default to on for auto, it defaults to last setting. Try just turning e-heat off and leave the rest of the climate on and see if that makes a difference.
 

breeves002

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The vibration is the AC compressor ramping up. You can hear it too especially if it is warm outside, it can be quite loud at first. All EVs and most Hybrid/PHEVs have electric AC compressors that operate the same was as the one on the Mach E.

e-heat is not the source of the vibration as it is a resistive element and water pump.

Once the system cools some the vibration will become much less noticeable or go away as the compressor ramps down (it's variable). Ford didn't isolate the compressor very well to avoid putting vibrations into the cabin.

Please note that even with AC selected off manually the compressor still may run.
 
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SpacePony

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It does not default to on for auto, it defaults to last setting. Try just turning e-heat off and leave the rest of the climate on and see if that makes a difference.
Interesting. I'll try that. Is it really slow to heat up if you don't use the E-heat? We're moving into spring now, but will be good to know for next winter. In my Volts I got pretty used to using "eco" heat, which meant it heated the steering wheel and seat, but just barely blew some warmth into the footwells. But my spouse desires a more conventional "comfort" setting.
 
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SpacePony

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The vibration is the AC compressor ramping up. You can hear it too especially if it is warm outside, it can be quite loud at first. All EVs and most Hybrid/PHEVs have electric AC compressors that operate the same was as the one on the Mach E.
So in this instance it's ramping up to dry out the air for the front window defrost, I presume. Yeah, that probably makes sense, since I noticed that it doesn't do it when it's more moderate (in the 50s), but did in the 40s. It's not actually very loud, but you can FEEL it in the pedals.
e-heat is not the source of the vibration as it is a resistive element and water pump.
Right, but I didn't know if it was some sort of a fan that blew through the resistive unit to get it into the HVAC system or something.
 

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I wonder if it could be battery conditioning kicking in at the cooler temps?
 

breeves002

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I wonder if it could be battery conditioning kicking in at the cooler temps?
Doubtful. That is just the resistive heater and a water pump as well. I've never noticed any vibration at cold temps. Only vibration is when the ac compressor kicks in.

So in this instance it's ramping up to dry out the air for the front window defrost, I presume. Yeah, that probably makes sense, since I noticed that it doesn't do it when it's more moderate (in the 50s), but did in the 40s. It's not actually very loud, but you can FEEL it in the pedals.

Right, but I didn't know if it was some sort of a fan that blew through the resistive unit to get it into the HVAC system or something.
Correct on the defrost part. The Mach E has a standard heater and evaporator core like any car. Normal blower motor. The resistive heater heats up coolant and pumps it through the heater core in the cabin.


The whole HVAC system is fairly complicated.
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